Book design will diverge down several paths and has a surprisingly healthy future.
1) E-books based on a reflow format (i.e., suitable for small devices) will be based on common style sheets and exhibit a fairly uniform appearance. There will be a set of small (in size) firms that customize and refine these style sheets. Publishers will mostly outsource the format conversion since the ever changing variety of devices requires continual reformating of material. There will be some firms that profit very well from providing this service.
2) E-books based on PDFs also will be very popular due to the variety of light-weight computing devices with large screens. (The whole PDF vs reflow format for e-books is misleading unless one assumes that small, palm-sized devices will completely replace all other forms of desktop, notebook, and tablet-sized computers.)
3) Some material traditionally only published in book format will shift to Web delivery and “book” design for this genre actually is Web design. Many challenges for publishers in this segment who have not yet figured out how to monetize Web sites. (If publishers have not figured that out in the last 15 years, will the next 15 years be much different?) Many opportunities for new publishing firms to emerge to fill the gap for producing and monetizing engaging content using digital media. Many opportunities for designers since elegant Web design is neither simple nor cheap.
4) Print-on-demand establishes a significant market operating in bookstores, libraries, big-box retail outlets, and direct shipping to consumers. All those books still need designing and the PDF byproduct can feed directly into pathway #2 above as well as #1 with conversion services offered in pathway #1.
5) Print book designers will still flourish as some publishers will realize that a niche audience is willing to pay a premium for a wonderfully designed book, heralding a surprising renaissance in book design. Also, print book designers can design PDF-based e-books with no problem since PDF is usually a byproduct in the print book design process.